- Bluebird bio will need to wait longer for a decision from the Food and Drug Administration on approval of two gene therapies it submitted last year, announcing Tuesday that the agency has extended its review in each case by three months to go over additional clinical trial data.
- The FDA now expects to decide on approval of beti-cel, Bluebird's gene therapy for the blood disorder beta thalassemia, by August 19, the company said. A decision on the biotech's rare brain disease treatment eli-cel, meanwhile, is now scheduled to occur by September 16.
- The extensions are the result of "additional clinical information" previously submitted by Bluebird, which the FDA judged to be a so-called major amendments to the company's applications. Bluebird noted, however, that the delay is not related to any new adverse events in tests of either therapy, both of which have been slowed in the past by safety concerns.
Bluebird's path to the FDA and, hopefully, to market in the U.S. has taken significantly longer than the company expected. The company, a pioneering gene therapy developer in many respects, won approval in Europe of beti-cel and eli-cel in 2019 and 2021, respectively. But disagreements with the FDA, along with clinical holds over safety, pushed back filings of each therapy with the U.S. regulator.
Now Bluebird has another three months to wait for the FDA to decide on approvals, news of which sent shares in the company down by as much as 7% Tuesday morning.
The extensions, however, aren't expected to impact the Priority Review status granted by the FDA to both applications. Bluebird is counting on that designation, which, in the event of an approval, provides a sellable voucher that can be used to speed up FDA assessments of new medicines. Typically, a voucher can be sold for between $75 million and $100 million, although their value has declined as more have been issued by the agency.
If approved, beti-cel and eli-cel would become the third and fourth gene therapies for an inherited disease approved in the U.S., after Roche's Luxturna and Novartis' Zolgensma. While many other gene therapy developers are targeting beta thalassemia, fewer are aiming at the disease eli-cel is designed to treat — a neurodegenerative disease called cerebral adrenoleukodystrophy.
Both treatments use lentiviruses to genetically modify patient cells outside the body. Once engineered to express either a version of the beta-globin gene (in the case of beti-cel) or the ABCD1 gene (eli-cel), the cells are infused back into patients, where they are designed to produce, respectively, functional hemoglobin and ALD protein, which in testing of each has shown dramatic benefits for patients with each disease.
Approvals would be major milestones for Bluebird and for the gene therapy field. But selling the therapies could prove challenging. In Europe, the company is withdrawing both treatments from market as it winds down its business there following problems securing reimbursement for the therapies. Only a few patients ever received treatment with beti-cel, which was sold as Zynteglo in Europe.